The present disclosure relates generally to simulating downhole formation environments and, more particularly, the present disclosure relates to a method and apparatus for automatically testing high pressure and high temperature sedimentation of slurries.
Subterranean drilling operations typically utilize drilling fluids to provide hydrostatic pressure to prevent formation fluids from entering into the well bore, to keep the drill bit cool and clean during drilling, to carry out drill cuttings, and to suspend the drill cuttings while drilling is paused and when the drilling assembly is brought in and out of the borehole. In certain drilling fluids, fine solids may be mixed into a slurry with a liquid component. The slurry may then be introduced downhole as part of the drilling process. The effectiveness of the slurry may depend, however, on the static sag property of the drilling fluid, which describes the tendency of a fine solid, such as barite, calcium carbonate, etc., to separate from the liquid component and settle. The static sag can result in variations in mud density in the wellbore, with the light density on top and the heavy density is at the bottom.
Tests to determine the static sag property of a drilling fluid typically are performed manually and generate limited density profiles. For example, current systems may use a syringe to manually draw a sample(s) from a particular area(s) of a test container, which limits the density measurement to the particular areas where the sample(s) were collected. Another test system uses a cup at a bottom of a test container to collect settled solids, which are then weighed to obtain a density, but such a method does not provide density measurements at particular locations within the drilling fluid. Moreover, the structural components of existing test apparatuses limit the pressures which can be applied to the drilling fluids, which, in turn, limits the types of subterranean formation which can be simulated. What is needed is an automated and robust way to test static sag of drilling fluids in a variety of simulated conditions.
While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.